1. Field of the Invention
The present invention relates to the field of optics and in particular to a light deflection system for the steering of a small diameter beam of light in a predetermined direction.
2. Description of the Prior Art
In the E. J. Torok et al, U.S. Pat. No. 3,752,563 there is illustrated a magneto-optic light deflector system that utilizes the stripe domains in a magnetic film as a diffraction grating. The angle of deflection of the light beam from the plane of the film is varied by varying the intensity of a magnetic DC field in the plane of the film or by varying the intensity of a magnetic DC field normal to the plane of the film. The orientation of the stripe domains is varied by varying the direction of the DC field in the plane of the film while the film's hysteresis is overcome by a magnetic AC tickle field that is oriented perpendicular to the stripe domains. The normally incident light beam is diffracted by the film-forming diffraction grating to generate a single zero'th order light beam, which is oriented along the optical axis of the normally incident light beam, and a pair of conjugate first order light beams, which are the light beams that are deflected along the new optical axes.
In the E. J. Torok U.S. Pat. No. 3,861,784 there is disclosed a programmable diffraction grating that utilizes the stripe domain diffraction grating of the E. J. Torok et al U.S. Pat. No. 3,752,563 that which further includes means for varying the separation of adjacent domain walls and the rotatable orientation of the parallel stripe domains. The resulting system is utilized to control the focus of a light beam that is directed upon the plane of the film. The apparatus includes a plurality of stripline arrays that are configured to permit the individual and selective control of the separation and orientation of the domain walls in each portion of the film. This selective control of the domain wall separation and orientation in each part of the film permits an arbitrary configuration of domain walls of substantially continuously varying spacing and direction. These varying domain wall arrangements permit the performance of various image processing functions.
In the W. A. Harvey et al U.S. Pat. No. 4,281,905 there is disclosed a magneto-optic light deflector system that includes two converging half-lenses of equal focal length, that may be formed from a single circular converging lens, a circular center portion of which may be removed and which may then be cut in half along a diameter. The two converging half-lenses are oriented superposed with their optical axes common and orthogonal to the plane of the magneto-optic light deflector with their optical axes aligned with the optical axis of the light beam that is directed normally incident to the plane of the magneto-optic light deflector. The two half-lenses parallelize the prime and conjugate first order light beams that are generated by the magneto-optic light deflector, which light beams are then focussed by a convex lens upon a screen or detector.
In these above discussed magneto-optic light deflector systems, the light that is utilized is a monochromatic light beam, such as is provided by a coherent laser light source. However, it is most desirable to utilize a multichromatic or multiwavelength light beam in a magneto-optic light deflector system, as for performing signal processing upon data modulated white light. However, because of chromatic aberration in a multi-wavelength light beam incorporating a magneto-optic diffraction grating, such prior art systems cannot utilize a multiwavelength beam.